This invention relates to a wedge-shaped vehicle barrier with flexible sling that may stop an errant vehicle. The vehicle barrier may be used in a variety of applications, including traffic control and security gates.
Currently commercially available wedge-shaped vehicle barriers use steel chains or steel linkages to anchor a wedge plate to a wedge foundation. While these steel chains and linkages may provide adequate strength during a vehicle impact, they also present various problems for both the wedge designer and wedge customer, such as high weight, susceptibility to corrosion, high noise when raising and lowering the wedge plate, and high part-to-part length variation, as discussed below.
Steel chains and linkages are heavy and require higher power mechanisms to lift the chains and wedge plate. Steel chains and linkages are often painted, powder-coated or galvanized. This provides only temporary corrosion protection for these components due to their exposure to the elements and the abrasive rubbing action they experience as the wedge cycles between open and closed positions.
As the wedge barrier opens and closes, the steel chain linkages will rattle against themselves and against other components in the wedge barrier. This chain noise is significant and creates a nuisance for security and other personnel stationed nearby. This noise also creates a less-desirable perception of wedge barriers that are installed at highly aesthetic and image conscious sites, such as corporate office buildings and data centers. Some wedge manufacturers place a rubber mat or similar sound-deadening material in the bottom of the wedge foundation in an attempt to reduce chain noise. Such mats or materials have no impact on reducing the sound of the steel chain linkages rattling against themselves, and such mats or materials become submerged in rain or runoff water causing them to rot over time.
Commercially available chains have significant part-to-part linkage variations in length as a consequence of the manufacturing process. As most wedges have four or more chains, the length variation between those chains results in non-uniform loads on each chain and across the wedge plate during open/closed cycling and during an impact, which causes the chains to wear more quickly and unevenly increasing maintenance and repair costs, as well as potentially damaging the chains and barrier and reducing the barrier's performance during operation and impact.
The wedge-shaped vehicle barrier with sling of the present disclosure may overcome these problems by using a high-strength, light-weight, low-noise, flexible sling that can be manufactured to more precise length tolerances in place of steel chains or linkages. There are several advantages the sling of the present disclosure may have as compared to a wedge that uses metal chains.
First, the ability to manufacture slings with more precise length tolerances enables each sling to wear more consistently and evenly and allows more uniform loads to be placed on each sling and across the wedge plate. Second, the slings are easier to install and replace due to their light weight and manageability. Third, chain linkages may “lock up” when changing position. For example, links in a chain may shift and may not immediately slide back into the ideal operating position when the wedge plate is raised. This causes the chain to “lock up” or “kink.” A sling meanwhile does not have a metal link to “lock up.” The rope-like fiber of the sling naturally orients into the ideal operating position when a wedge opens and closes. Fourth, fatigue and cracking in chains is often difficult to detect while any abrasion or wear on the sling is more noticeable and more gradual. Accordingly, a fatigued chain may suddenly fail and break without any prior warning, meaning the chain will no longer be useable and potentially requiring the barrier to be removed from service until a new chain can be installed. However, fatigue and wear on a sling can be noticed sooner (while still functioning for a period of time unlike metal chains) and replaced prior to failure. Fifth, slings are much lighter than steel chains, making them easier to replace and potentially requiring less power to raise the wedge plate. Sixth, slings are much less susceptible to corrosion over time. Finally, slings significantly reduce the operating noise generated by a wedge barrier as the barrier plate is raised and lowered, eliminating the resulting nuisance.